Start major refactoring of recurring_todos. Started with creating new recurring todos.

All current and new tests pass

app/models/recurring_todos/abstract_repeat_pattern.rb

@@ -0,0 +1,42 @@
+module RecurringTodos
+
+  class AbstractRepeatPattern
+
+    def initialize(user, attributes)
+      @attributes = attributes
+      @user = user
+    end
+
+    def build_recurring_todo
+      @recurring_todo = @user.recurring_todos.build(mapped_attributes)
+    end
+
+    def mapped_attributes
+      @attributes
+    end
+
+    def attributes
+      mapped_attributes
+    end
+    
+    def map(mapping, key, source_key)
+      mapping[key] = mapping[source_key]
+      mapping.except(source_key)
+    end
+
+    def get_selector(key)
+      raise Exception.new, "recurrence selector pattern (#{key}) not given" unless @attributes.key?(key)
+      raise Exception.new, "unknown recurrence selector pattern: '#{@attributes[key]}'" unless valid_selector?(@attributes[key])
+
+      selector = @attributes[key]
+      @attributes = @attributes.except(key)
+      return selector
+    end
+
+    def valid_selector?(selector)
+      raise Exception.new, "valid_selector? should be overridden in subclass of AbstractRepeatPattern"
+    end
+
+  end
+  
+end